Can you visit a site with an expired domain name? whats up with that anyways?

To visit the site of an expires domain name, you would need to already know the IP address of the server. All the domain name does is allow your computer to look up the IP address of the server (i.e. 127.0.0.1). Without the domain entry, it will be very difficult to obtain such information though. You can also use a site like www.archive.org to view what the site USED to look like.

No, you can't. The host of the site may have taken away the account of the web master of that site because of missed payments, illegal material, etc.